Effects of Beta-lactoglobulin Gene Polymorphism and Some Factors on Milk Quality and Yield in Dairy Cattle of Kashmir, India

Abstract

Background: Polymorphisms in candidate beta-lactoglobulin genes are associated with traits of economic importance in cows and are related to milk composition, quality, production as well as cheese-production. The objective of the study was to evaluate the effects of breed, season and polymorphism on milk quality and yield in Jersey and Crossbred Holstein Friesian cows. Methods: The quality traits studied were fat %, lactose %, protein %, SNF, density and ash while quantity traits were average monthly milk yield, protein yield and fat yield. The beta-lactoglobulin gene exon IV (262 bp) was screened for polymorphisms by PCR-RFLP using BsuRI (Hae III) enzyme. Result: Our investigation revealed only two patterns AA and AB in both the breeds under study. BB genotype was absent. AA genotype was most abundant in Jersey cows (0.68) and crossbred HF cows (0.56). A allele frequency was highest in Crossbred HF cows (0.72) and Jersey cows (0.66). In Jersey genotype AB was observed to be responsible for high milk yield, protein and fat yield in each season whereas it was genotype AA of Crossbred HF cows affecting milk yield, protein and fat yield. In crossbred HF cow, genotype effect was observed to be non-significant (p>0.05) on all quality traits and effect of season was significant on lactose % and fat %. In Jersey cows, genotype and season effects were significant (P<0.05) on fat % concluding that the breed, season and genotype affectmilk quality and yield.